Actually it's well documented Alnico mags alter tone in pups just as they do in speakers. Ceramic is considerably brighter for example. There are many Alnico formulae's but Alnico 5 is the most popular. As the number increases the pup becomes brighter with more output, all else equal.

I personally have found I prefer Alnico 5's for MM's. The sound is a noticeably less clear, less bright, more raw vintage tone. I've had about a dozen MM's. I've had twice as many J's but haven't paid enough attention to the mags to really tell if I have a preference there or not. But I could probably go back and look at my reviews and figure it out. Took me a while to figure out with the MM's cause I really wasn't paying any attention but eventually a pattern emerged. With fewer pups and knowing what there were, it was easier to tell.

Actually it's well documented Alnico mags alter tone in pups just as they do in speakers. Ceramic is considerably brighter for example. There are many Alnico formulae's but Alnico 5 is the most popular. As the number increases the pup becomes brighter with more output, all else equal.
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IMHO, this is nonsense, because no matter what kind of magnet you use the magnetic field will have the same properties. The only magnet property that can affect sound is how strong the magnetic field is, and you can achieve weak or strong magnetic field with alnico and with ceramic or neodymium or whatever. (although you could technically make a stronger neodymium magnet than an alnico magnet, but you probably wouldn't want to anyways, in pickups at least)

Thanks to the TBLers who stopped by my booth at NAMM. It was a very busy ........so I won't get into it.

Re. Alnico vs. ceramic. It's not voodoo. On the fairly gross level, Alnico
is conductive and ceramic is not; therefore even coupled with identical coil
structures, the inductances will be different, and eddy current losses will
"soften" the sound of the Alnico loaded pickup. Then there's the shape and
density of the magnetic fields which will be very different between ceramic
and Alnico. Many golden-eared guitarists can hear the difference between
Alnico 2 ("sweeter") and Alnico 5 ("crunchier") Strat pickups. In fact, new
Alnico 2's sound a bit like old Alnico 5's.
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You can find pieces like this all over the web, on pup manufacturer sites, in Guitar Electronics For Musicians.

Even so, it would be nonsense to me as well, but I've heard the difference, at least in MM's.

Because a pickup pole piece (which is not necessarily the magnet) is within the coil of a pickup it has an effect on the changing electromagnetic flux that induces the currents in the coil. We are talking about tiny effects here but I would expect that it is these effects that help define the tone of a pickup. Then there is the grade of copper used in the coil, the dielectric effect of the insulation used on the copper, the interaction of the guitar string itself (if electric currents weren't induced in the string then the pickup would not work), and last but not least the 'strength' of the magnet. Perhaps some of these effects are over-sold, but not all pickups are born equal. The nice linear equations in text books describe idealised electrical components operating in free space - the real world isn't that simple.

Because a pickup pole piece (which is not necessarily the magnet) is within the coil of a pickup it has an effect on the changing electromagnetic flux that induces the currents in the coil. We are talking about tiny effects here but I would expect that it is these effects that help define the tone of a pickup. Then there is the grade of copper used in the coil, the dielectric effect of the insulation used on the copper, the interaction of the guitar string itself (if electric currents weren't induced in the string then the pickup would not work), and last but not least the 'strength' of the magnet. Perhaps some of these effects are over-sold, but not all pickups are born equal. The nice linear equations in text books describe idealised electrical components operating in free space - the real world isn't that simple.

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AFAIK only the hysteresis of the string material is of importance, because the magnet is there to magnetize the string which then, by moving, affects the magnetic field (and a voltage is induced)

glad you posted that cuase I always wondered why the grounding to the bridge was useful in cutting down hum. I really don't remember reading about the string itself carrying current before as opposed to simply inducing a current in the pup (don't have much of a grasp of the principles of this stuff just know what I read and experience).

A lot of the subtle tonal aspects get lost in the mix but the Alnico MM's I've played are different played to music.

FWIW: saw Rick Turner posted to a TB thread the other day (regarding the TBL blip of his I threw out previously) and thought he might jump here himself but guess not.

I design and build electric basses and pickups under the Turner, Renaissance, and Electroline brand names.

There are several "models" one can look at to explain how magnetic pickups work. One of them is the "moving magnet" model, whereby the magnet merely charges the string which then becomes a moving magnet over a coil...inducing current to flow. Then there's the "disturbing the stationary magnetic field" model whereby the field exists in stasis which is interrupted by the moving string which has ferrous material in it. Then there's the "variable shunt" model, especially with humbuckers, whereby the string is a moving "keeper" between two magnetic poles, and the conducting of the magnetic field between the poles is varied by string vibration.

In fact, no one "model" is sufficient to explain everything we can hear, and there may be more than one mode of operation going on at the same time unless a pickup is designed specifically to supress some modes and stress another.

There is a sound to each pickup design which is specific to the dynamic three dimensional interaction among string, physical coil size (3 d space through which the flux field flows), and magnet structure which includes the magnet and any magnetically conductive pole pieces. This sound is independent of the electrical filter characteristics of the coil's inductance, capacitance, and resistance or group delay/phase issues.

The bottom line is that yes, Alnico magnet pickups sound different from ceramic magneti pickups...